1. Field of the Invention
This invention relates to electrically-operated vehicle systems, and more particularly to such a system including an improved electrically-operated automotive vehicle and an electrified roadway for supplying electric current to the vehicle.
2. Prior Art
Electrically-powered automotive vehicles are well known and conventionally are powered by a storage battery pack which supplies the electrical energy for operating the vehicle on the open road, with the vehicle including charging circuitry to enable recharging of the batteries as by connection to a conventional electrical supply. Such vehicles provide low pollution, economical transportation, but generally are seriously limited in the distance they can travel between battery charges. Further, operating the vehicle on batteries alone over long operating periods between battery recharging causes substantial discharge of the batteries resulting in greatly reduced battery life as the battery cycles between charged and discharged condition.
Electrically-operated vehicles are also known which are capable of operation both from a battery pack and from an outside source of electrical power such as overhead trolley wires or energized trolley rails or tracks. However, maneuverability of such vehicles has generally been severely limited and the battery-operation has generally been intended only for a limited use such as transferring between trolley lines, turning the vehicle, or other short maneuvers. Accordingly, such vehicles have generally not been found satisfactory for general public use.
Inductive coupling between the vehicle and the roadway energization system has also been proposed; however, inherent in such a system is large and weighty coupling apparatus including conductor windings and winding cores. Overall, such a system adds substantial weight to the vehicle and is expenseive to manufacture.
Another known electrically-operated vehicle employs a battery pack for supplying the power to the electric motor drive, with an alternate, self-contained power source such as an internal combustion engine provided to drive a generator for re-charging the batteries and/or providing electrical energy to the drive motors when not operating on the batteries. While this system overcomes the inherent range limit of vehicles powered by batteries alone, the system is relatively expensive to construct, inefficient to operate, and suffers from most of the pollution problems of internal combustion engine-operated vehicles.
It is also known, for example from U.S. Pat. No. 1,859,343, to provide an electric motor-driven vehicle with electrically conductive tires which contact a series of conductors imbedded in the top surface of a roadway to complete an electric circuit beween the imbedded conductors and an overhead line which is engaged by a trolley. The vehicle is able to maneuver over the width of the roadway, within the confines of the imbedded conductors, so long as the trolley maintains electric contact with the overhead line. The patent also discloses the use of an engine-driven generator as an alternate power supply to enable the vehicle to proceed from the specially-designed roadway onto an ordinary road surface.
Another system is shown in U.S. Pat. No. 4,139,071 where an electrified traffic lane is provided with at least two spaced parallel electrical contact assemblies mounted with their top surfaces flush with the road surface and in position to be contacted one with a wheel on each side of the vehicle. The contact assemblies each requiring a predetermined weight thereon to maintain electrical contact with the vehicle wheels. The vehicle employs electrically-conductive tires which are the pickup contact with the conductors for energization of electrical motors within the vehicle. This system presents a safety hazard to potential foot traffic along the roadway in that the system can be energized by any adequate weight and remains energized when a stationary weight is on a roadway electrical contact assembly.